How to Make It
In a large bowl, toss the watercress with the mint, basil, cucumber, chile, shallot and tofu.
In a small skillet, combine the vegetable oil with the nuoc mam, lime juice, brown sugar and garlic and cook over moderate heat just until bubbles form around the edge of the skillet, about 1 minute. Pour the dressing over the salad and toss. Mound the salad on plates, sprinkle with the sesame seeds and serve.